Embodiments described herein relate generally to switch fabrics and more particularly, to sending data through switch fabrics (e.g., Clos networks).
Known switch fabrics can be multi-stage networks that provide connections between multiple input ports and multiple output ports. Thus, through a switch fabric, a first peripheral device operatively coupled to the switch fabric can send data to a second peripheral device operatively coupled to the switch fabric.
A three-stage Clos network, for example, has a middle stage connected between an input stage and an output stage. Each stage includes multiple modules. Each input stage module has multiple input ports and is operatively coupled to each middle stage module. Similarly, each output stage module has multiple output ports and is connected to each middle stage module.
As the data traverses the switch fabric, each stage determines to which subsequent stage to send the data. To make these decisions, a header (e.g., a packet header) can be used. Each stage of known Ethernet switch fabrics, for example, perform layer 2/layer 3 (L2/L3) packet forwarding, lookup and classification. In some known switch fabrics including more than a single stage, such forwarding, lookup and classification functions can significantly increase the end-to-end latency of the switch fabric. Further, adding additional peripheral devices and/or stages to the switch fabric can significantly increase the end-to-end latency of the switch fabric.
Additionally, known Ethernet switch fabrics often do not ensure that data packets sent from a first peripheral device to a second peripheral device traverse the switch fabric using the same path. Accordingly, packet order is not preserved at the output of the switch fabric and the second peripheral device reorders the data packets, causing further latency and increasing buffering requirements.
Thus, a need exists for a switch fabric that has a relatively low end-to-end latency when compared with known switch fabrics. Additionally, a need exists for a switch fabric that preserves packet ordering.